Failed DPF „Passive“ Regeneration (TDI 1.6)

Dear everyone,

Would you be willing to do some analysis on the DPF issue/confusion (there is also some info on premium diesel) ?
I bought a used VW Golf 2012 TDI 1.6 (diesel, 165 000km real mileage), and I wanted to do a passive regeneration while driving on the highway for the second time. I played around with this newly purchased software called “VAG DPF” that shows live data of DPF related values (via Vgate iCar Pro OBD). Once the engine reached normal 90 degrees, I proceeded to drive in 4th gear and kept the revs at ~2400rpm, later on in 3d at ~2900rpm for ~45 minutes: the result is my app did not show the value “Soot Mass Calc (g)” as decreasing, but it just kept steadily increasing (although at a slower pace than in the city). The purpose of a failed passive regeneration to my knowledge is “DPF Output Gas Temp” did not reach the required ~500°C, but only peaked at 300°C at while staying mostly at ~250°C. Are these exhaust temps abnormal when engine is rev’ed high?

The attached screenshot is VAG DPF software live data screen before my attempt at passive regeneration. It says “86 km since last regeneration” - if the regen did happened 86 km ago, I can not confirm 100% it and I did not have the software then, but I did do a ~30 minute drive at ~2500rpm on the highway with regular diesel. This time, however, I had the software in hand I had the tank with 50% premium diesel (with additives) and 50% regular diesel. Now the deal with premium diesel here in Lithuania is some people are afraid of it, because some people, including my father who bought a used volvo, have destroyed their catalytic converters by fully clogging it with the loosened debris from the engine after filling with premium fuel. That is why I filled my tank only with 50% of premium fuel this time, since I do not know the state of the engine internals. a.k.a. I take it easy on the cleaning of the internals in the first few runs.

THE QUESTION IS - what are the conditions that need to be met for passive regeneration to happen/ for exhaust temperatures to get to 500C?

The general talk around here is that only a few gas stations provide with a decent quality regular diesel, one of them is fuel from “PkN Orlen”. So I bought the premium fuel from there, just as my father did (and does)

(EGR was 100% closed at ~3000rpm)

Thank you!

Good idea to clearly describe your objective. Are you trying to

  • determine which gas stations sources the best fuel quality?
  • determine if you VW’s exhaust system is starting to fail or already faulty?
  • Something else?
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Only 17 questions to go.




Sorry about it…
I am afraid why passive regeneration isn’t happening as it should and is something wrong about the exhaust system, because exhaust temperatures don’t go high with high engine revs

I see at least 4 things as to why no regen is happening or even needed.
Only 86 km since the last one.
Less than 5 hours since the last one.
Differential pressure 6 hPa (.08 psi).
Inlet/outlet temps almost the same.
So far looks like all the symptoms of NOT needing a regen.
Sorry but I have to burn a question.
Your “system” does not see the need for a regen. Why do you feel the need, or even think you could force a “passive regen”?

Damnit only 16 questions left.


lol ok, understood.

I just wanted to try to manually initiate passive regeneration with high rpm’s, and since while doing I got an increased value of soot (calculated) instead of decrease, i thought maybe i started blocking the exhaust system with loose carbon residue from using premium fuel…

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Have you read @Tester ‘s link? I think you’re worried about nothing.

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I admit I was quick to disregard the link, which I quickly ran through and came to the conclusion “i know what passive and active regeneration is because I googled it”. Now I see it highly depends on the model and isn’t so straightforward. I recall now that I have heard local mechanics and “google articles” apply the very simplified concept of passive regeneration to every diesel engine out there.
Back to reading

What is the problem you’re trying to solve regarding the engine behavior?

Well, once in a while idling revs are fluctuating, and a diesel engine service diagnostician told me the injector is going down. I thought maybe it is possible that injectors are clogged and I could try to clean them with some additives or premium fuel. But by doing that I wanted be sure that in case there is a lot of debris, I wont clog the exhaust system (by monitoring the situation live with OBD)

the idea of a passive regen is that the ECM will decide when to do it. by definition, you cannot force a passive regen, you are then doing a manual regen.
as far as I know, there isn’t a certain drive cycle to initiate a regen. The ECM will look a the needed data and do it when needed (of course, VW could have almost anything programmed, so who knows, :wink: )

VW may have software available to do a manual regen if that is what you want to do. But you will need a scanner and that software to make it happen.

as @PvtPublic stated, your vehicle doesn’t see the need for a passive regen, so it isn’t doing one yet.

as for clogging the exhaust with fuel additives, that shouldn’t be a concern as long as you are using diesel additives. Are you using UltraLow Sulfur diesel in your VW?
I hope by “premium” you don’t mean premium unleaded…

At first I thought ECM decides on active regeneration, while passive is a natural process dependent on necessary driving conditions…
What would be the definition of active regeneration by you?

Active would most likely be a “commanded” regen. done at the dealer with dealer level equipment. But maybe you could get a better info if you try a VW specific forum, there are a couple of them out there.


Manual/Active/Forced/Parked regen are all pretty much the same thing. As @PvtPublic said, they are most likely done with dealer level software. My big trucks have a “Parked Regen” switch on the dash, where when switched on, the ECM will run a manual regen if it sees that conditions are appropriate for it. My smaller diesels do not have such a switch.

you have the screenshot of the current status of your system- and it shows 14grams of soot. It likely won’t want to run one until it is over 40 grams, maybe higher (I’m not sure where VW would want Regen to start at.)
Run the vehicle as normal for a week, and recheck your numbers- mindful of diesel soot levels, and distance since last run. If it takes several hundred miles to run a passive regen, then you are probably doing well.
If it happens to frequently, then you may have other issues.
at 14 grams and 86 km since last done, it looks healthy to me.

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Thanks for clearing it up. will do